1. Field of the Invention
The present invention relates to an electronic blurring correction apparatus capable of electronically correcting blurring of images.
2. Description of the Related Art
Among the image-capturing apparatuses for capturing a static image or dynamic image using a solid-state image-capturing device, there are quite a number of image-capturing apparatuses which can be held in hand to perform photography. In such image-capturing apparatuses, when, for example, the brightness of a photographic subject is low, camera shake occurs easily because the shutter speed is slow. Further, in in-car cameras and the like as well, camera shake can occur due to vibration of the vehicle in motion.
Various technologies for correcting such camera shake are proposed in the prior art, among which there are, for example, an optical camera shake correction technology which moves the optical system in accordance with vibration, a sensor shift camera shake correction technology which moves a solid-state image-capturing device in accordance with vibration, and an electronic blurring correction which corrects blurring by processing a captured image.
Among these technologies above, regarding the electronic blurring correction technology, there is one for dynamic images, which holds the position of a photographic subject in an image constant by changing the clipping position of the image for each frame in accordance with a camera shake. However, this technology is not designed for preventing blurring of an image within one frame, and thus cannot be applied in static images.
On the other hand, various electronic blurring corrections apparatuses which can be applied in static images are also proposed.
(1) For example, Japanese Patent Application Laid-Open No. 2002-135659 describes a technology in which a layer of a group of photoelectric conversion elements, Y-direction CCD shift register layer, X-direction CCD shift register layer, and a layer of a group of charge accumulation elements are stacked on a semiconductor by means of the 3-dimensional integrated circuit technology to configure an image sensor, and the phase of the transfer clock of the Y-direction CCD shift register layer and the phase of the transfer clock of the X-direction CCD shift register layer are controlled so that charges can be transferred in both the plus and minus directions.
Suppose that blurring occurs while exposure is performed using the image sensor with the above configuration. Then, charges which are generated on the layer of a group of photoelectric conversion elements are transferred in parallel to the Y-direction CCD shift register first, and then transferred by the Y-direction CCD shift register by the amount corresponding to the Y-direction components of a blurring signal.
Next, the charges which are transferred in the Y-direction are transferred in parallel from the Y-direction CCD shift register layer to the X-direction CCD shift register layer, and then transferred by the X-direction CCD shift register layer by the amount corresponding to the X-direction components of the blurring signal.
Subsequently, the charges which are transferred in the X-direction are transferred from the X-direction CCD shift register layer to the layer of a group of charge accumulation elements and accumulated.
The above-described operation is carried out every time when the blurring signal is changed by the size of the photoelectric conversion element, and the layer of a group of charge accumulation elements is scanned when the exposure is ended, whereby an image signal is output.
In this manner, by changing the shift amount of the CCD shift registers in accordance with the image blurring amount to change the transfer path of the charges, an image signal with no image blurring can be obtained.
(2) Further, Japanese Patent Application Laid-Open No. 2005-198148 describes a technology with respect to a solid-state image-capturing device for generating an image signal corresponding to light from a photographic subject, in which a plurality of photoelectric conversion sections, which are arranged in a biaxial direction, and charges, which are read out from the photoelectric conversion sections, are transferred in any direction of the positive and negative directions of the biaxial direction with respect to the biaxial direction, and charges which are transferred by arbitrary number of pixels are mixed with the charges which are read out from the photoelectric conversion section and correspond to the pixels at the transfer destination.
Accordingly, when displacement occurs between an image based on the charges read out from the photoelectric conversion section to a charge transfer section, and an image based on the charges accumulated thereafter in the photoelectric conversion section, due to camera shake along a transferable direction in the charge transfer section, an image obtained before the camera shake occurrence can be moved so that it matches an image obtained after the camera shake occurrence, so that images with blurring corrected in the biaxial direction can be combined.
However, in the technology described in Japanese Patent Application Laid-Open No. 2002-135659 described above, since the multilayer integrated circuit with the three-dimensional structure is required, it is expected that the production cost of the image-capturing device increases.
Furthermore, the technology described in Japanese Patent Application Laid-Open No. 2005-198148 described above is configured such that the transfer path for moving images in the biaxial direction is formed in the image-capturing section, the pixel aperture ratio of the pixels decreases and whereby the sensitivity decreases. In addition, since the transfer path in the biaxial direction is provided in the image-capturing section, smear increases, compared to a conventional interline transfer CCD having a transfer path in a uniaxial direction.